Power management device and system

ABSTRACT

An intelligent user-side power management device (PMD) that is comprised of an optional energy storage unit and can interface with a utility grid or microgrid to eliminate power theft and efficiently provide clean energy to the users of the grid while helping the grid to do smart demand response management, particularly for renewable energy based grids that need to efficiently manage the slack due to the large variability in power generation through these energy sources.

CROSS REFERENCE OF RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application No.61/514,103 filed on 2 Aug. 2011 which is hereby incorporated by way ofreference. This application further acknowledges the prior patentapplication U.S. Ser. No. 13/100,957 filed by the same applicant on May4, 2011 and is hereby incorporated by way of reference in this patentapplication.

FIELD OF THE INVENTION

The present invention relates to the power management of mini gridsystems for use in power management unit and/or device system arrays,which can be activated externally for a temporary period or permanentlyand that is plugged in and/or rechargeable and portable. It can beutilized with a whole range of energy sources that provide eitherfluctuating (like solar panels, dynamos and the like) or constant power(like a wall adapter or utility grid) as output. In addition the powermanagement devices (singular and/or multiple power managementunits/devices in operation may be referred to and configured as such foruse as a power management system) are capable of being stackable andbuilt with theft deterrence and overload detection capabilities. Theyare enabled to output a variety of voltages and variable amount of powerthat may be used to run a variety of end appliances, including cellulartelephones, personal stereos, memo recorders, televisions, lights,computers, fridges.

BACKGROUND OF THE INVENTION

The renewable energy boom during the recent past has brought somesignificant advances to the energy sector, but renewable technologiesand the conventional electricity grid are not necessarily suited foreach other. A couple of major problems exist in this area. First, themodern grid operates on AC power, while renewable sources for example,solar panels generate DC power. The conversion from DC to AC createsavoidable inefficiencies in the grid, which is further aggravated whenthe power is converted from AC back to DC to operate modern DCappliances such as cell phones, laptops, and LED lamps.

A second problem with renewable sources is their inherent variability inpower output for example, solar panels being shaded, which warrantslarge amount of storage in order to ensure a consistent and reliablepower delivery to the nodes of the grid. In particular, duration ofpower supply (number of hours in a day) in rural areas of developingcountries and quality of supply (voltage and frequency) is highlyuncertain and intermittent. This is both expensive and difficult toscale for the grid operator. Furthermore, traditional grids suffer frompower theft, making the already-expensive renewable energy sources evenmore expensive. For example, in India energy theft is a major issue inrural communities, where distribution companies incur AT&C losses ofover 58% most of which is due to theft and pilferage.

Moreover, the electricity distribution companies in these areas chargeconsumers a minimum fixed monthly fee irrespective of powersupply/consumption. Thus, in several cases people pay more forelectricity than what they actually consume just to maintain theconnection. Most electrical appliances today are DC powered and the mostpromising renewable source of power is—‘Sun’ which too generates DCpower. Thus, in areas where generation and most of the consumption is inDC, there is a need for DC transmission and distribution to reduce powerlosses through several layers of conversion.

Prior art patent publications US 2010/0207448 A1 and US 2012/0080942 A1are considered as relevant to the present invention. However, the citedprior art basically describe ideas and concepts rather than concretetechnical solutions to the problems. These ideas and concepts have beendiscussed in several publications prior to the disclosure of theadmitted prior art.

However, the existing grids supplying A.C. power or hybrid power(combination of A.C. & D.C. power), suffer from distribution problems.In particular, quantum of generation of non-conventional and variablevoltage power (D.C.) is not constant due to natural uncertainty.Further, the A.C. supply from the grid is totally irregular particularlyin rural areas, and so is the situation for hybrid supply. In gist,there is no reliable system and process available for AC or DC powerdistribution to ensure equitable and substantially regular power supplyby eliminating power theft, and maximizing the generation/distributionefficiency by implementing distributed maximum power point tracking andintelligent energy demand response techniques.

The foregoing examples of the related art and limitations relatedtherewith are intended to be illustrative and not exclusive. Otherlimitations of the related art will become apparent upon a reading ofthe specification and a study of the drawings.

SUMMARY OF THE INVENTION

It is therefore, an object of the present invention to propose a smartpower grid comprising one or more sources of energy generation that maysupply constant or variable amounts of power, a central controller withoptional remote monitoring capabilities that can control a cluster ofpower management devices (PMDs) that are used for efficient monitoring,controlling, metering, equitable distribution of electrical power to theconsumers corresponding to different energy demand-generation scenarios,and eliminate power theft.

Another object of the present invention is to propose at least one PMDwith optional internal storage capacity interfaced with the smart powergrid acting as distributed storage to allow amortization of storage costacross all users in the smart grid that in turn reduces the capital andoperating costs for the grid owner.

A still another object of the present invention is to propose at leastone PMD interfaced to a smart grid which is enabled to accommodateexternal storage device to increase storage capacity.

A further object of the present invention is to propose at least one PMDinterfaced to a smart grid, which is configured to implement aneffective demand-response management on the smart microgrid andequitable power distribution, to several appliances including devicessuch as refrigerators, air conditioners, heaters, having inherent slackto supplement or act as the primary storage attached to the PMD.

A still further object of the present invention is to propose a PMD thatuses the voltage on a grid and is enabled to convert the supply voltageinto useful DC, AC, or hybrid voltages to operate a large variety ofconsumer appliances.

Yet another object of the present invention is to propose a PMD thatoptionally comprises has internal, external or hybrid storage, which canbe used for remote slack management by the smart grid to controlcharging and discharging of this storage to provide reliable power toconsumers even during low generation levels without significantlyinvesting on central storage facility.

Another object of the present invention is to propose a PMD, which isenabled under wired or remote communications mode with the central gridcontroller to achieve maximum power point tracking of variable powergeneration sources in a distributed manner without additional devices asof prior art.

A still another object of the present invention is to propose a processfor automatic detection of power theft during transmission, distributionand consumption of power through a PMD interfaced to a smart grid.

Yet another object of the present invention is to propose a PMD withmeans for metering the generation and consumption of power includingprocessing of deposit/credit/outstanding payment data.

A further object of the present invention is to propose a PMD thatallows the users to increase local storage and consumption or decreasethe power consumption corresponding to increased/decreased power supply.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1—shows a block diagram of a Power Management device (PMD)interfaced to a DC-micro grid according to the invention.

FIG. 2—shows a block diagram of a Power Management device (PMD)interfaced to an AC-micro grid according to the invention

FIG. 3—shows a block diagram of a Power Management device (PMD)interfaced to a hybrid grid (AC+DC) according to the invention

FIG. 4—shows an architecture of the smart grid of the invention withcentralized storage and PMDs with their internal distributed storage.

FIGS. 5A,5B,5C—schematically show a process for implementing maximumpower point tracking under different generation consumption conditionsaccording to the invention.

FIGS. 6A & 6B—schematically illustrate the process of theft detectionaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The approach is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” or “some” embodiment(s) in this disclosure are notnecessarily to the same embodiment, and such references mean at leastone.

Accordingly, there is provided a Power Management Device (PMD) that canbe interfaced to a smart microgrid (using AC or DC power, or hybridpower) to address the prior art problems. The smart microgrid isconfigured to be of modular construction such that it can cater for asfew as tens of PMDs vis-à-vis consumers and expanded to operate as autility grid by combining several smart microgrids with communicationmeans provided between them. This modularity interalia makes it feasibleto provide grid power without incurring huge capital expense ofextending the utility grid to remote areas. The invention describedherein is an intelligent user-side Power Management Device (PMD) for asmart microgrid that may use distributed storage.

The smart microgrid of the invention works with A.C, D.C., and hybridpower, from source to appliances. The grid is capable of working but notnecessarily limited to solely working on the premise of distributedstorage in which each household or business contains its own energystorage, amortizing the cost of energy storage across the entire userbase and allowing for seamless scaling. The smart microgrid is has avery low susceptibility to power theft. Further, the invention allowsimplementing the techniques of distributed storage and maximum powerpoint tracking without the use of any additional devices. The smartmicrogrid according to the invention comprises at least the following:—

One or multiple conventional or non-conventional power generationsources that may generate constant or variable amounts of power forexample, solar, wind, biomass, micro, hydro, and the existing powersupply from the grid.

Distribution wiring that takes power from the generation station to oneor more fanouts, the fanouts acting as intermediate distributionstations for a cluster of consumers. From the fanouts, power isdistributed to the consumers who each have a PMD.

A central controller located close to the generation source that metersthe total amount of power going into the microgrid and communicates withevery fanout. The fanout meters the power going through it andcommunicates with every PMD that is distributing power through it. Allthis local communication is done using a medium that can be wired,wireless or a combination thereof as the communication protocols used bythe PMDs can be customized for any communication medium. The PMD isdesigned to work with pure AC power, pure DC power or a combination ofthe two, thereby catering to all forms of power generation in a mostefficient manner. Each PMD among other features is provided with atleast one microcontroller which is independent of whether the inputpower is AC or DC, or hybrid.

The central controller can comprise of a GSM module to do wirelesscommunication with a remote central server where all informationcollected in the microgrid is stored. This server is connected to theinternet to allow grid operators to monitor microgrid operationremotely. The central server also sends commands to the GSM module tocommunicate with any specific PMD, and further to troubleshoot thetechnical problem of the microgrid or turn it on/off. The centralcontroller can also use any other technology for communication to theremote central server such as radio, CDMA, wired communication usingEthernet etc.

The PMD is capable of accepting DC, AC, or a hybrid power backing ofinputs, provides metering information to the grid for power usage,outputs different DC voltages and a standard AC voltage to operate awide variety of appliances, communicates with the grid for slackmanagement and safe operation, charges the backup internal storage toprovide power during grid downtime, and provides a user interface togive relevant information to the user. Furthermore, it can be activatedand deactivated to allow controlled levels of consumption, i.e., thedevice will remain active until a certain amount of power flows throughit, similar to how a pre-paid cell phone remains active until theaccount runs out of balance. When the PMDs are used in a plural manner adistributed power storage network results in creating the basis for apower management system.

In one embodiment, for AC input into the PMD, three levels of circuitprotection is provided for example:

A varistor is used in parallel to the supply to protect the circuit fromvoltage spikes.

A fuse (resettable or non-resettable) or a circuit breaker is put inseries of power supply to prevent current spike

In the main meter, a current transformer meters the current flow in thecircuit. If the current flow exceeds a threshold limit, the microcontroller shuts off the relay to protect the internal circuit of thePMD including the appliances the PMD is powering

To meter AC power, as seen in FIG. 2, the PMD samples the voltage andcurrent of the incoming AC waveform. The sampling rate is selected to bemore than double the frequency of the waveform to prevent aliasing. Themicro controller reads these values through its Analog to DigitalInterface. The voltage is read using a step down transformer and avoltage divider. The transformer provides magnetic isolation between thepower and controller circuitry to protect the digital circuits.

Another way to measure the voltage is to adapt a voltage divider andoptocouplers that use different power supplies to isolate the digitalcircuitry from surges in the power circuitry. The current is measuredusing a current transformer. It can also be measured using a currentsense resistor, hall effect sensor. There are also integrated circuitsavailable for metering AC power which can also alternatively, be used inthe PMD for metering the power going through it.

The power inputted through the main meter, in one embodiment, is causedto:

output 5VDC and 13VDC by using DC-DC converters. The DC-DC converter for13VDC output can however, be eliminated if the user does not need strictvoltage regulation. In this case, this output can be directly connectedto the local 12V storage that the PMD charges and the voltage willfluctuate corresponding to change in storage voltage, operate a varietyof standard AC appliances, charge the local storage through an AC-DCcharger.

According to this embodiment as depicted by FIG. 2, the DC outputs aregenerated through current limited DC-DC converters. When the outputcurrent goes beyond this current limit, the voltage drops to maintainthe power output as constant. This voltage is compared against athreshold using an analog comparator and when it goes below thethreshold, the switch (a PMOS or NMOS) is turned off by changing itsgate voltage. Accordingly, output voltage can be safely controlled at alow cost.

The PMD comprises a battery charger having an AC to DC converter and aPWM controlled voltage feedback circuit to precisely monitor the outputcharging voltage of the converter. This charging voltage can be modifiedusing a digital potentiometer, which is controlled by the microcontroller. The micro controller receives signals from the smart grid toincrease or decrease PMD's power consumption to which it responds bytuning the digital potentiometer. The digital potentiometer sets thenegative feedback reference voltage of the battery charger, which altersthe PWM of the circuit and changes the charging voltage.

The battery charger is calibrated such that a particular differencebetween charging and battery voltage leads to a particular amount ofcurrent flow into the battery. Hence changing this charging voltage canprecisely control the amount of power going into the battery.Alternatively, this power can be controlled by using a current senseresistor, a current amplifier, and an analog comparator in addition tothe AC-DC battery charger. The negative feedback reference voltage onthe analog comparator can be changed to alter the PWM of the circuit andthereby change the amount of current flow into the battery. This localstorage is attached to an inverter, which converts DC to AC. During theperiod, when the grid is unable to supply sufficient power to serve theloads, the controller switches to the inverter power thereby reducingthe load on the grid. The grid sends this message to the PMD to switchto battery storage instead of grid power. However, the grid can continueto supply power to charge the battery as per power availability.

In another embodiment of the invention, when the input power to the PMDis high voltage DC for example, between 150-250VDC, which can however beincreased or decreased by using an appropriate DC-DC converter insidethe PMD to generate different useful voltages using the modified inputvoltage range, a large variety of renewable energy sources can be usedto power the PMDs.

A circuit breaker in the form of a circuit protection is provided toprevent the internal circuitry of the PMD from being damaged due to avoltage spike in the grid or current surge due to a short-circuit on theuser side. This circuit protection may be either a mechanical orelectrical device, which disconnects the PMD from the grid in the eventof such a spike, and only reconnects the PMD after some user action(i.e. flipping a switch, pushing a button, etc.) This is a similarconcept to the circuit breakers commonly found in homes on normal ACgrids; however the form of the circuit breaker may be different thanconventional devices to suit the special requirements of a DC, or AC ora hybrid grid.

For example, circuit protection is done with unidirectional zenerdiodes. It can also be done by using high power transistors whose gatevoltage is controlled by a digital circuit that outputs high/low basedon whether the input voltage is within the prescribed range or not. Forexample, a voltage divider network made of resistors can be used tomeasure the input voltage, which is compared against a threshold voltageusing an analog comparator. The output of this comparator is connectedto the gate of the transistor to turn it off when the grid voltage isbeyond prescribed limits and keep it on till it returns within limits.

The DC-DC converter in the PMD has a dynamically adjustable outputvoltage. This voltage is also the charging voltage of the storage.Through grid communication, the PMD learns when it should consume moreor less power and accordingly adjusts a digital potentiometer connectedto the negative feedback node of the DC-DC converter. Tuning thispotentiometer, the output voltage of the converter is changed, which inturn changes the power going into the battery, vis-a-vis the total powerconsumption of the PMD. No AC to DC converter is necessary here sincethe input power is also DC. This makes the system more efficient.Alternatively, any technique that allows one to change the PWM of theDC-DC converter can be used to tune the power going into the localstorage.

The main meter uses voltage dividers to measure input voltage andcurrent sense resistor technique to measure the current. In the All DCPMD (PMD-A), the controller does not have to measure any frequency,power factor, etc. because in DC, all power is real power. Each PMD isalso programmed for a maximum allowed current through it. Whenever themeter senses a higher current, it turns the meter off for a few secondsand indicates overload through a red LED on the UI. The controller thenturns on the meter back by switching on all the output switches. If theoverload condition is removed, the meter stays in the on state,otherwise it repeats this behavior.

In one embodiment of the invention, the user interface (UI), in the PMDprovides the following data to the user:

Instantaneous power consumption on an LCD screen or through segmenteddisplays based on readings from the metering module.

Total power left for consumption (in the case of prepaid power). This isdetermined by calculating the difference between the total power forwhich the PMU is activated and the amount of power consumed, which thePMU has measured since activation.

Power history: An optional on-device SD card or similar storage devicecan be provided to record the history of power consumption on the PMU.The SD card can then be inserted into a computer to read the history.Alternately, the data can be communicated through the modem on an onlineportal on the Internet or can be acquired by the central controllerthrough grid communication.

Fault indicators are used on the casing of the PMU to display anycommunication errors or other fault conditions such as short circuit oroverload. A reset button is provided on the PMU casing to return thedevice to normal operation after the fault has been remedied. The systemis allowed to reset itself periodically in this state to check if thefault state is removed, in which case the system gets back to the normalstate, else falls back into the fault state.

The PMD has an optional DC to AC inverter to cater to AC appliances aswell. According to the invention, the internal storage can be anyrechargeable battery pack as the DC-DC converter takes care ofconverting the input grid voltage to the appropriate battery voltage forcharging and/or creating an output voltage to run appliances. ThePMD-controller can be programmed to charge the particular battery thatis used in the PMU. The controller also switches between charging,storing and discharging the battery based on its communication with thegrid. An example of this communication is a 2-bit input stream that thegrid sends to the PMD.

One bit determines whether the PMD can be charged or not and the otherbit determines the priority to charge this PMD's storage as opposed tothe storage of other PMDs in the grid. Based on the state of the batteryand this input stream, the PMD controls the battery switches and allowsthe battery to charge or maintain its state. Depending on the state ofthe battery, the PMD also controls if the battery should be allowed todischarge or not in order to ensure that the battery does notover-discharge. An alternate example for how the communication forswitching the battery could work is that the grid could just send asignal that determines how much of a PMD's battery should be charged.Thus, if the grid sends a signal representing 40%, all the PMDs wouldset a charging rate (allow more or less current into the battery) to gettheir batteries to reach 40% of their charged state. Since aprogrammable microcontroller in the PMD interfaces with the gridcommunication and controls the internal storage, the PMD can interfaceand adapt to any communication system/protocol that the grid designer oroperator might want to use to manage its storage loads.

The DC output voltages and input voltage are connected in parallel totwo different stacking connectors placed on the PMD. This allows two ormore PMD units to be stacked on top of each other. Since input voltageis stacked, a single input cable can charge/monitor the associatedstorage of all stacked PMDs simultaneously, and the meter of the PMDthat is directly connected to the grid will measure the total powergoing into all PMDs and communicate that back to the grid. By stackingthe outputs, one can draw more power from a single output connector ofthe PMD stack as all the stacked PMDs can now provide power to the loadconnected to the specific PMD. Thus, if one PMD can supply 15 W throughthe 5VDC output, three PMDs can supply 45 W through the same 5VDC outputafter stacking.

The limit to how many PMDs can be stacked is determined by the powerrating of the output connector based on which the power rating of therest of the circuitry in the PMD is decided. Alternately, stacking canbe implemented by disintegrating the controller, circuit breaker, meter,and DC-DC converter into one unit and the rest of the power management(storage, different DC and AC output voltages, A/D Comparator, switches)into another ‘less intelligent storage unit’. Then a stack can compriseof one of the former unit that connects to the grid and does the safetyand metering, whereas the other units can act as the latter storagedevices that are centrally controlled with this former unit. This canreduce the cost of stacking excess storage devices as the additionaldevices will have less functionality, which is being supplemented by thecentral controller.

In another embodiment of the invention, as can be seen in FIG. 3, thePMDs are enabled to operate under multiple power generation sourcesgenerating both AC and DC power and the consumption is both AC and DC.In this case, the PMD-microcontrollers are configured to perform thefollowing additional functionalities:

The main meter still meters total DC power going through the PMD toserve loads through the different DC outputs or the DC-AC inverter toserve AC loads when AC power is not available. In addition, there is anAC meter in the PMD that meters the AC power coming into it. This meteris useful because if the load needs AC power and the supply is also AC,then the power can flow straight to the appliance through the 240VACoutput and the inverter switch can be opened. Whenever AC power isavailable and there is an AC load on the PMD, the inverter is shut downto avoid energy losses and power flows straight from the AC meter to theload.

The main converter used in this PMD is a DC-DC+AC-DC converter than canconvert both kinds of power to a single 13VDC output that is used tocharge the local storage and power a 5VDC output and the inverter.

The inventive PMDs are configured with an optional stacking feature aswell. The PMDs have male/female stacking connectors, which allowmultiple PMDs to be physically and electrically connected together. Oncestacked, the DC and AC outputs of one PMD get connected to the otherstacked PMDs. This allows the user to draw more power from the stackedoutputs. To stack DC outputs, the DC voltages on the respective PMDs areconnected together in parallel with each other. To stack AC outputs,each PMD has a ‘phase syncor’. This phase synchronization, in oneembodiment, is implemented by introducing delays in the AC wave suchthat the phase of the AC waves of the new PMD entering the stack is thesame as those already existing on the stack before turning on theconnection between the AC outputs.

According to an advantageous aspect of the invention, the PMD allows theconsumers to purchase power using a prepaid model. For example, theconsumers purchase energy credits to recharge their meters. These creditdata can be transferred into the PMD using various options—wiredcommunication, wireless communication using GSM, Bluetooth, infrared, orany other medium that allows data transfer into the PMD. The metercalculates the amount of power being consumed and keeps counting downthese energy credits. When the PMD runs out of energy credits, thePMD-controller turns off the main switch/relay to avoid any furtherpower consumption.

As soon as the PMD is recharged with credits, the switch turns back onand power starts flowing again. This prepaid purchase model has thefollowing advantages:

It allows the users to pay for exactly the amount of power consumed; iteliminates payment defaults; and it makes the users aware of their powerconsumption, which tends to reduce energy wastage

In another advantageous feature of the present invention, the smartmicrogrid that uses the power management device (PMD) on the consumer'send and a central controller on the generation side, is enabled toimplement the process of maximum power point tracking in a distributedfashion. MPPT, as depicted by FIGS. 5A-C, is a technique commonly usedto maximize the power output of variable power generation sources bymodifying load creating conditions for the generation source that forceit to output the maximum power that can be derived based on theavailable sunlight or wind speed respectively. For example, solar panelshave a maximum power point for a particular amount of solar radiation.If a consumer tries to draw more current from the panel than what isavailable at the maximum power point, then the voltage across the paneldrops significantly and the total power from the panel also drops down.

Similarly, if the current drawn is reduced too much, then the voltage ofthe panel approaches its open circuit voltage, which also reduces theproduct of voltage and current and hence reduces power output. Toprevent these conditions, the prior art uses expensive maximum powerpoint trackers to control the output voltage and current of the panelsin order to maximize the power output. Typically, these maximum powerpoint trackers are current controlled DC-DC converters that control theoutput current of the system to maximize output power. MPPTs are alsoknown to be installed centrally where a system has its central storageor from where it sells back power to the grid.

As opposed to the prior art, in the disclosed invention, use ofexpensive maximum power point tracker is eliminated and MPPT isimplemented in a distributed manner through intelligent communicationsbetween the central controller (39), the fanouts (38) and the PMDs,which interalia makes the inventive system more efficient. In oneembodiment, the maximum power point tracking for solar arrays isimplemented as under:

The central controller (39) measures the DC voltage and DC current ofthe array of solar panels. By multiplying the voltage and current, thecentral controller (39) measures the power output of the solar array.

The central controller (39) then sends a signal to the fanout (38)s toincrease their power consumption by a small amount. This signal istypically in the form of a percentage.

The fanouts then transmit this signal to all the PMDs that it iscontrolling.

The PMDs, based on the state of charge of their batteries and the signaldescribing the % increase in power, tune their in-built digitalpotentiometer to increase the power going into their local storage. Iftheir storage is full, then they can also directly control power goinginto devices such as heaters, air conditioners, fridges etc. whichinherently have slack.

The fanout collects information from the PMDs on how much powerconsumption has been increased and relays this information back to thecentral controller. If the total power increased is less than what thecentral controller warranted, then the fanout sends a further increasesignal to the PMDs and does this till the power is increased to the sameamount that the central controller required.

The central controller now again measures the total power output of thepanels. If the load increased is much more than the panels could handle,then the voltage of the panels is likely to go down significantly, andthis would lead to an overall fall in power output. In this case, thecentral controller transmits commands to the fanouts to reduce powerconsumption till the panels start outputting the same levels of higherpower as earlier. Conversely, if the power output went up, the centralcontroller asks the fanouts to further increase their power consumptiontill it detects the peak power position of the solar array.

To ensure grid stability, a central storage (battery) may also beinstalled in the system. The size of this storage depends on the size ofthe microgrid and the time it takes to receive data from all the fanoutsand PMDs. With the central storage, the peak power can easily bedetected by adding a meter to measure the power coming out of thecentral storage. As long as there is no power coming out of the centralstorage and all power is coming out from the panels, the centralcontroller continues to command the fanouts to increase theirconsumption. The moment the central storage starts supplementing thepower output of the panels, the central controller asks the fanouts toreduce power. The object of this MPPT process is to always allow maximumpower to flow out of the generation source, which implies that minimumor zero power should be supplied from the central storage, therebyreducing the capacity vis-à-vis cost on central storage.

In a further embodiment of the invention, a process for detection ofpower theft in the smart microgrid interfaced with a cluster of PMDs isprovided. Firstly, the inventive PMDs are configured to be tamper-proof.In one embodiment of the invention, the PMDs have a light sensor andthis sensor is covered with the casing of the PMD. As soon as anunauthorized person opens the casing, the PMD shuts itself off and sendsa tamper signal to its fanout, which in turn relays this signal to thecentral controller. The central controller through GSM informs the gridoperator which meter has been tampered, who can then take appropriateaction. Alternatively, a touch sensor, electrical contact or any otherform of sensing device that can identify when a meter casing is opened,can be used to detect meter tampering after which the tamper signal ispropagated in the system through communication.

However, the second type power theft which is known as “DistributionLine Tampering”, constitutes stealing power directly from the lines orexternally tampering the PMD's meter without opening the casing. Thecurrent invention is capable, as depicted in FIGS. 6A-B, of detectingand curbing this form of theft as well. The smart microgrid of theinvention typically has more than one distribution line and each linecovers multiple consumers. In one embodiment, during a no-tampercondition, the central controller communicates with the PMDs through thefanout to measure the voltage drop on the distribution wire between thegeneration and the PMD. This voltage drop allows the central controllerto measure the line resistance between the central controller and eachPMD under normal conditions.

Through measurement data of the line resistance, the central controller(39) determines how much power can be consumed based on generation andline losses on the microgrid. The central controller, throughcommunication with the PMD and fanout, also determines the consumptionby each fanout (38) and their PMDs. If the sum of line losses andconsumption of the PMDs/fanouts is more than the total power coming outof the central controller, then the central controller generates atamper flag, and informs the grid operator via text message through GSMor any other form of communication to the grid operator's monitoringsystem which of the distribution lines has been tampered and if requiredturns off power supply on that distribution line. The central controllercan keep power off for a while and start supply again to see if tampercondition has been removed. If it still exists, the central controllercontinues to keep the power supply off.

As shown in FIG.-4, a smart microgrid comprises one or more energygeneration sources. If it is a DC microgrid and one of the generationsources produces AC power, then this generation source is connected to arectifier that converts the AC power into DC power corresponding to thedistribution voltage of the microgrid. If the generation source is DC,then no rectifier or voltage converter is necessary as the distributionvoltage can be made to match the generation voltage to avoid any energylosses due to additional conversions. Conversely, if it is an ACmicrogrid and generation is in DC, then an inverter (40) is needed toconvert the DC power into the AC voltage used for power distribution.

If there is also an AC generator generating power at a voltage differentthan the distribution voltage, then a transformer and phase synchronizer(not shown) is used before supplying power to the microgrid. The powergenerated, AC or DC then flows through a central controller (39) usingan electrical wire. The output of the central controller (39) isconnected to a plurality of fanouts(38) each assigned for a group ofPMDs (A,B,C) using distribution wiring through which power flows betweenthe central controller (39) and the fanouts (38). The fanouts (38) arethen connected to all the PMDs (A,B,C) using distribution wiring todistribute power to all the PMDs to run the loads. To allow the centralcontroller(39) to communicate with the fanouts (38) and the fanouts (38)to communicate with the PMDs, a communication link is setup betweenthese devices. This link can be wired or wireless. The centralcontroller (39), fanout (38) and PMD (A,B,C) have communication hardwareinside them to which this wired or wireless link is attached. Forexample, if the link is wired, then in one embodiment the centralcontroller (39), fanouts(38), and PMDs (A,B,C) can have RS485transceivers. If the link is wireless, the central controller (39),fanouts (38), and PMDs' (A,B,C) can have wireless modems such as radiotransceivers, zigbee modems, wifi modems, or anything else that allowswireless data transfer.

The central controller(39) can also be connected to a long distancewireless transceiver (45) such as GSM modem which allows remotemonitoring of the microgrid as the central controller (39) can now senddata collected in the microgrid to a remote central server (not shown)from where this data can be easily accessed. The smart microgrid may beprovided with a central storage (42), and a charge controller (41).

As shown in FIG. 1, the Power Management Devices (A), at the user's endcomprises at least one circuit protection (1), a switch (2), and a mainmeter (4). At the user end, the PMD(A) comprises, a local storage (7)controlled by a battery manager (6), and an on-off switch (5). EachPMD(A) has a controller (17) for monitoring and controllingcommunication with the grid central controller (39), ensuring maximumgeneration and equitable distribution of the power including metering,theft prevention, distributed maximum power point tracking, and revenuemanagement. PMD(B) interfaced to a AC-grid similarly comprises a circuitprotection (30), a switch (31), and a meter (32) at grid operator end,and a local storage with a battery manager (7,6), a battery charger(33), a DC-AC inverter (16), at least one DC-DC converter (29), andon-off switches (34) at the user end, including the microcontroller(17). PMD(C) interfaced to hybrid grid (AC+DC) comprises two eachsub-meters (32,4), two circuit protection (30,1), switches (31,2), amain meter (37), and one each DC-DC, and AC-DC converter (36), a batterypack with battery manager (6,7), a DC-DC converter (14), a DC-ACinverter (16), a plurality of switches (11,12,15) including amicrocontroller (17).

The micro controller section (17) of the PMD(A,B,C) collects, processes,and stores power data, displays relevant information to the user,communicates with the outside world (such as the utility grid andactivation device), controls actuators such as relays (20) on the PMD,and interfaces (21,23,22) with auxiliary devices such as tamperdetectors (25). The central element (28) of the controller (17) is theprocessor, with peripheral circuitry to supplement the functionality ofthe microcontroller. The major components of the controller section,which may be internal to the microcontroller or implemented in theperipheral circuitry, are:

Analog-to-Digital Converter (21) to sample the voltage and currentwaveforms of the power signal and transmit them to the microcontroller(17). The ADC (21) also may be used to sample other useful signals suchas temperature, backup battery voltage, light levels, etc;

Digital Inputs and Outputs (I/O) to control external devices (such asrelays, switches) and receive external signals (such as those frompushbuttons or tamper detection devices);

Non-Volatile Memory (NVM) to store relevant parameters and fordatalogging. This includes EEPROM (generally used for parameterstorage), flash memory (generally used for datalogging), or any othermemory technology which stores data in the long term;

Grid Communication Interface (18) to allow the microcontroller (17) tocommunicate with the utility grid. This may be implemented as a wiredinterface (ie RS-485, Ethernet, etc.), power-line interface, or wirelessinterface (ie Zigbee, optical, etc.);

Activation and Debugging Interface (27) to allow the microcontroller(17) to communicate with credit recharge devices and in-field debuggingdevices. This may be implemented as a wired interface (ie RS-232, USB,etc.) or wireless interface (ie Bluetooth, infrared, etc.);

Real Time Clock (19) to keep track of the time and date.

Grid Communication Interface

The GCI relays information to and from the utility grid. Informationsent to the utility grid from the PMD may include self-identificationinformation, power and energy usage, tamper information, and otherrelevant data. Information sent to the PMD from the utility grid mayinclude requests for data, control commands (such as those fordistributed load management algorithms), time synchronization commands,etc.

Activation and Debugging Interface

The activation and debugging interface allows further interaction withthe meter than the user interface provides. In one embodiment, it is aclose-range communication interface used by devices in direct proximityto the PMD. In this embodiment, the activation and debugging interfaceis comprised of an infrared transceiver on the PMD, which cancommunicate with an external device called the Activation Dongle.Activation Dongles contain power credits and are used by grid operatorsto recharge the meters with additional credits for users with pre-paidaccounts. As the name implies, this interface may also be used to gainadditional information about or debug PMDs.

User Interface

The user interface informs the users of relevant power usage and accountinformation. This information is displayed on a screen, with additionalindicators such as LEDs if necessary. In one embodiment, the screen is atwisted-nematic (TN) numeric LCD screen, with several LEDs to indicatevarious things.

Conventionally, this interface would display information such as powerusage in watts and energy usage in kilowatt-hours. However, since theseare pre-paid meters and to improve consumer understanding of powerconsumption, the power and energy information can be displayed inunconventional units related to money and time rather than absoluteengineering units. According to one embodiment of the invention, thescreen alternates between three quantities: current power usage,expressed as credits/hour; total running time remaining, taking intoconsideration current power usage and credits remaining in the account;and finally, credits remaining in the account.

Also, an LED is provided which blinks at a rate proportional to powerconsumption to supplement the credits/hour information displayed on thescreen. Finally, LEDs may be provided which indicate fault conditionssuch as meter overload or tampering.

In a preferred embodiment of the invention, the known technique ofdistributed storage is implemented without the use of any additionalstructural device, for de-centralizing energy storage in the grid, whichinteralia allows extending the power storage to the end nodes (homes,businesses, etc.) and only retaining a very small amount at the centralstorage (42) for grid stability. Each end node (PMD) contains a battery(7) and an inverter, allowing it to use its own battery power under thecommand of the central controller (39). This technique utilizes areliable, fast communication means throughout the grid to executedistributed load management algorithms and ensure judicious energydistribution on a low-generation day. Distributed storage also allows amore scalable grid infrastructure as the amount of storage in the gridscales directly with the number of users.

According to the invention, the batteries are placed at all end nodes(PMDs) of the grid and controlling the PMDs through communicationbetween the microcontrollers (17) and the central controller (39), aprecise control is exercised over the amount of power that the grid isconsuming from the generation sources at any given time. Not only canthe charging of the batteries (7) be turned on and off, but an entirePMD can be seamlessly switched from grid power to battery power, therebytemporarily eliminating its consumption of power from the grid. This isespecially useful in microgrids with limited, non-scalable generationsources such as solar power. This form of backup capability although canbe provided by the centralized storage (42), however, the distributedstorage adds to the capability of automatically alternating grid usagebetween different end nodes, thereby fairly rationing a limited amountof energy between all of the different end nodes of the grid.

In order to implement the distributed storage technique, a battery (6),a battery charger (3,33,36), and an inverter (16) is provided at the endnode including a communication means to control these devices in the endnode (PMD) from the central controller (39). In one embodiment of thepresent invention RS-485 communication protocol is used on the microgridto connect all of the end nodes (PMD) with the controllers in the grid.Different form of wired communication, power line communication, or awireless network is also possible. Additionally, a central controller(39) is provided in the grid which keeps track of the power, energy, andgeneral state of all of the nodes in the grid.

The method of operating the invention can be described with reference tothe drawings as under:

FIG. 1, when the PMD receives high voltage DC, the power goes throughthe Circuit Protection (1), the Switch (2), and the Isolated DC/DCConverter (3), which are connected using wire or through traces on aPCB. The DC-DC converter (3) outputs a low voltage DC, which interaliapowers the micro controller (17) and another parallel trace on the PCBor a wire goes through the main meter (4). The main meter (4) isconnected to the controller (17) which sends voltage and currentreadings to the Analog to Digital Interface (21) of the controller (17).These readings are used by the processor (28) inside the controller (17)to meter the power going through the PMD (A).

After the main meter (4), power goes into the loads through various ACand DC outputs as shown in FIG.-1. Power going into these outputs iscontrolled by the controller (17) through a switch driver (28) thatturns switches (11,12,15) on or off. If the switches are on, power goesinto the load.

If the load requires 13VDC it goes directly into it through an output DCconnector since the output of the isolated DC-DC converter (3) is 13VDCas well. If the load requires 5VDC (as necessary for USB powered loads),a DC-DC converter (14) is used to convert 13VDC to 5VDC and then throughan output DC connector power goes into the load. If the loads require ACinput, then power goes through a DC-AC inverter (16) that converts 13VDCto the appropriate AC voltage (240VAC in one embodiment) and then powergoes into the load through an output AC connector.

The DC output voltages are attached to separate voltage dividers thatare in turn connected to the analog pins of the controller (17). Thecontroller senses changes in the output voltage and whenever there is anoverload state, the output voltage falls since the DC-DC converters (14)in the PMD are current limited. When this voltage falls below athreshold, the appropriate switches (11, 12 or 15) are shut down througha signal that goes from the switch driver (20) to the switch. After themain meter (3), power also goes in parallel to the local storage (7)through a switch (5) and a battery manager (6). This battery manager (6)is connected to the local storage (7) and it sends data on battery'sstate of charge, input and output current to the controller (39), whichhelps the controller (17) to evaluate how much power should be sent intothe battery (7). The switch is again controlled by the controller (17)through its switch driver (20) to turn battery charge/discharge on oroff.

In another embodiment the method of working the invention, when thePMD(B) is receiving AC-input, as depicted in FIG. 2, is that the powerafter the main meter (32) goes into the battery charger (33) and/or tothe 240V output. The power from the battery manager (6) goes intoswitches (11,12) from where through the DC-DC converter (14) the PMD (B)provides DC outputs to the loads. The remaining steps of operation issubstantially similar to that performed by PMD(A).

In a still another embodiment, the method of working the invention, whenthe PMD (C) is receiving hybrid power (AC+DC), as depicted in FIG. 3,from the grid, is that different forms input power AC or DC come intothe PMD (C) through different input connectors. They pass throughcircuit protection (1,30) and they get metered separately. Aftermetering, the AC power goes directly into the AC output through a switch(31) or it goes into the combined converter (36) to generate thedifferent DC outputs. When the switch (35) is open, the switch (15) isclosed and when the switch (15) is open, the switch (35) is closed.

The high voltage DC power goes into the combined converter (36) to getconverted into usable low voltage DC. The remaining steps of the methodto be performed by the PMD(C) is identical to that of PMD (A).

BEST MODE AND EXEMPLARY MEANS OF USE

An example as to of how the different elements of the inventioncombinedly and synchronously operate the inventive power-managementdevice in a smart microgrid system, is provided herein below:

A plurality of Solar panels (43) are provided for generation of energysay total 2 kWp capacity;

A central storage (42) of capacity of at least 500 Wh is located toprovide 15 minutes of backup for grid stability during which thedistributed storage procedure optimizes power generation from the panels(43) and ensures grid stability;

A DC-DC converter (41) provides a constant voltage to the inverter,which is equivalent to the battery voltage;

A Central inverter (40) converts DC power from the solar panels (43)and/or batteries (7) into 240VAC;

A central controller (39) is installed in the power generation stationenabled to meter total power transmitting into the grid and communicateswith different devices of the smart microgrid, including the PMDs.

Main distribution line carrying 240VAC.

At least one Fanout (38) from where the wires branch out to reach acluster of consumers, the number forming the cluster can beincreased/reduced based on population density and power consumption,

User-end of the PMD (B) is provided to each consumer being connectedthrough the fanout (38),

A Local storage device (7) inside every PMD is arranged at user-endbeing connected to the PMD with a battery charger,

An Optional inverter may be placed at consumer-end to provide AC backuppower when microgrid power is unavailable, and connected to the PMDthrough a switch,

Appliances are connected to the power coming through the PMD, and

A Communication medium, for example, twisted pair wires to implementRS485 communication protocol, from the central controller to the fanoutand from the fanout to every user-end.

In the inventive smart microgrid system having the Power Managementdevices as disclosed herein, the generated power flows in followingsequences:

-Solar Panels->DC-DC converter->Battery and/or Inverter->CentralController->Fanout->Individual PMDs->Appliance and/or local batteryand/or inverter.

Similarly, the communication commands/information can flow between thefollowing devices:

Sender Receiver Central Controller Fanout DC-DC converter Fanout PMDCentral Controller DC-DC Converter Central Controller

This is only one example of how communication can flow. It is possiblefor every element in the grid to interact with each other directly aswell if necessary. This hierarchical communication technique makes thegrid more modular and scalable. For instance, if a PMD (B) has to beadded to the grid, it only needs to indicate its presence to the fanout(38). If a full fanout (38) has to be added, the addition of the fanout(38) is to the central controller (39) by sending an appropriatecommand.

Possible Technical Solutions Provided by the Invention Under DifferentConditions: Condition A

This condition assumes that Power consumed by the appliances used by theconsumers is less than the solar panel's total generation. Without thePMD and central controller, the solar panel is disabled to operate atits maximum power point (MPP) leading to wastage of power.Alternatively, the PMD and the central controller, when operatingtogether, shall be enabled to implement the solutions as under:

The central controller (39) communicates with the DC-DC converter (41)to measure the total power output of the solar array (43).

If historical generation data is available, the system is enabled topredict the total likely generation of the solar array at a location,and at that time. A step climbing technique is then used to reach themaximum power point.

If the central controller (39) detects that the PMU is not operating atMPP, a command is transmitted to the fanout (38) to increase its totalpower consumption.

Every fanout (38) has a pre-allocated energy capacity based on the totalnumber of PMD (A,B,C) to be supplied with power. Based on the totalenergy that a fanout (38) has already consumed at a particular time ofthe day, from it's daily quota/ration, the central controller (39)prioritizes the fanouts (38) in order of least consumption of theirdaily quota. For example, if there are three fanouts (38) that have aquota of 3000 Wh, 1500 Wh and 5000 Wh and they have consumed 20%, 50%and 70%, respectively of their assigned capacities, the centralcontroller (39) commands for example, fanout 1 to increase it's powerconsumption with a higher priority than fanout 2. Similarly, fanout 2 isprovided power with a higher priority than fanout 3. This techniqueensures an equitable power distribution.

Similar to the fanouts (38), the PMDs (A,B,C) are allocated energycapacities as well. Using the same priority technique, as described in(d) hereinabove, the fanouts (38) ask the PMDs (A,B,C) to increase theirpower consumption by specific percentage, or by an absolute amount.

The PMDs increase their power consumption by storing this extra power intheir local storage (7) by changing their battery charging current. ThePMDs can also use this extra power by operating additional applianceslike refrigerators, air conditioners, raising water through a pump, atconsumers end.

The central controller (29) then measures the new power consumption.

The central controller (29) also measures the power being drawn from thecentral storage (42).

If power is not drawn from the central storage (42), then that wouldindicate that the consumption is still less than the potential powergeneration. So the central controller (39) once again asks the fanouts(38) to further increase power consumption.

The process is repeated till some power is drawn from the centralstorage (42), at which point the central controller (39) ask the fanouts(38) to marginally reduce their consumption to avoid draining out powerfrom the central storage (42).

The fanouts periodically rotate between different PMDs to ensureequitable distribution of power to all the PMDs connected to it.

Condition B

This condition assumes that Power consumed by the appliances through thePMDs is more than what the power generators can generate.

This situation indicates that a significant amount of power is drawnfrom the central storage (42),

The central controller (39) asks the fanouts (38) to reduce powerconsumption using the priority technique as described in Condition Ahereinabove.

The fanouts (38) then ask the PMDs to stop charging their batteries (7),

If the reduction in power is still not sufficient, the fanouts (38) shutdown power supply to the PMD's (A,B,C) using a priority scheme describedin Condition A,

The PMDs having no or less power supply, automatically switch over touse their local storage (7) to continue power supply to the appliances.

This condition is maintained until the central controller(39) asks thefanouts (38) to increase their power consumption

The fanouts periodically rotate between different PMDs to ensureequitable distribution of power to all the PMDs connected to it.

Condition C

This condition presumes that a PMD is tampered to steal electricity:—

As disclosed earlier, the PMD has a tamper detector on it which can bein the form of a light sensor, which is connected to the PMD'scontroller.

As soon as the PMD casing is opened to tamper the internal circuitry,the tamper detector/light sensor detects an unauthorized access andsends a signal to the micro controller(17),

The micro controller (17) shuts down the main switch stopping powersupply to the appliances,

The micro controller (17) also sends a tamper flag to the centralcontroller (39) indicating that the PMD (A,B,C) has been tampered,

The central controller (39) communicates a notification to the gridoperator about this tamper,

In the case that the tamper is done by disconnecting/corrupting thecommunication between the PMD and central controller (39), the centralcontroller (39) communicates a notification to the grid operator for thesame.

Condition D

This condition applies when power is stolen by tampering thedistribution lines (see FIGS. 6A and 6B):

The central controller (39) communicates with the fanouts (38) and thePMD (ABC) to measure the transmission wire resistance between thegeneration station and every connection,

This combined resistance allows the central controller (39) to evaluatehow much power is consumed on the distribution lines for a certainamount of power drawn by the entire grid,

The central controller (39) meters the total power drawn by each fanout(38) on the microgrid.

For example, the total power going into the microgrid from the centralcontroller (39) to a fanout (38) is 1.5 kW. The total power loss due toresistance on the distribution lines for this load is 105 W (7% ascalculated by the central controller (39) based on wire resistancecalculations). Now, say, the fanout (38) indicates indicating that it isdrawing only 1 kW by calculating the combined power drawn from each PMD.Thus, the central controller (39) detects (39) that 395 W of power isbeing stolen on the distribution line.

The central controller (39) then communicates this tamper message to thegrid operator who inspects the line to detect theft.

The central controller (39) can also be programmed to turn power supplyoff for this entire line and periodically check if the tamper conditionis removed by briefly turning the power supply back on.

An Example of Distributed Storage Technique Used by the Invention:

Consider a 2 kWp solar-powered smart microgrid serving 10 homes. On anaverage on a clear sunny day, assume that the solar panels generate atotal of 10 kWh. Each of the 10 homes has a PMD that is attached to alocal storage. These PMDs have an energy quota, which is decided basedon the type of connection the consumer selects, consumer preferences, orit can also be set based on historical data of the consumer's powerconsumption.

Since renewable sources of power such as wind and solar have variableand substantially unpredictable generation levels, a distributed storagetechnique and a maximum power point tracking technique (see FIGS.5A,5B,5C) makes power distribution equitable and more reliable for suchsources.

The energy quota of all the consumers when added up is say, 10 kWh,which the microgrid is likely to generate and sell on an average day offull sunshine. The problem arises when the generation levels increase ordecrease, which is what this invention addresses.

A decrease in generation level from 10 KWh implies that less than 10 kWhcan be sold to the consumers over the day. However, the essence of theinvention is that whatever power is available be distributed equitablyamong all the users and simultaneously debar a small fraction of usersfrom exausting all the generation by consuming more power within a shortperiod. To ensure equitable distribution, according to the invention,the central controller (39) monitors what percentage of energy quotaallocated to a PMD is used up at a certain point of time, andaccordingly prioritizes power supply to those PMDs who have used a lowerpercentage of their daily quotas. Below is a hypothetical data snapshotof the daily quotas of 10 consumers and how much they have used at aparticular time of day:

PMD Quota (kWh) % Used Up* Energy Left (kWh) 1 1.00 30% 0.70 2 0.50 50%0.25 3 0.75 10% 0.68 4 2.50 40% 1.50 5 0.50 20% 0.40 6 1.50 80% 0.30 71.00 45% 0.55 8 0.25 10% 0.23 9 1.50 40% 0.90 10 0.50 90% 0.05

This information is automatically recorded in the grid according to theinvention, as the PMDs are metering the amount of energy consumed andthe fanout and central controller can get this data from them at anypoint.

The maximum generation that this hypothetical microgrid can do is 2 kW.Now, the problem arises on two counts:

Generation is Low & Power Demand is High

Assuming that instantaneous generation in the grid has reduced to 1 kW,i.e. 50% of peak capacity which is the maximum power point of the solarpanels at this stage. Hence, if the system attempts to draw more power,then the panels' voltage vis-a-vis the total power output shall reducebecause the panels are disabled to wont operate at their MPP. Furtherassuming that the instantaneous energy demand at this instant is 1.5 kW,the microgrid has to decide where to channel the available power (1 kw)and how to meet the excess demand of 0.5 kw.

Without limiting the scope of the invention, application, and presumingthat all these 10 PMDs are connected to a single fanout (38), thecentral controller (39) transmits a signal to the fanout (38) indicatingthe amount of power that the fanout (38) can consume (in this case 1kW). The fanout (38) then sends commands to individual PMDs prioritizedby decreasing % energy quotas used up by the PMDs, to start switchingover from microgrid supply to their local storage (7) to continuepowering their connected loads. The fanout (38) can also send commandsto the PMDs, in the same priority order as described hereinabove, toreduce the charging current of their local storage to reduce theiroverall power draw. If reducing the charging current reduces the totalpower draw to the desired level, then the PMDs don't need to be turnedoff from grid supply. Once the fanout (38) measures that the total powerconsumption has come down to 1 kW, then it stops sending ‘turn off’signals or ‘reduce charging current’ signals to the PMDs. This processis repeated periodically and the set of PMDs asked to reduce their powerconsumption are changed for equitable energy distribution.

This simple prioritizing and rationing technique ensures that availablepower is always distributed evenly and equitably to PMDs and alsoensures operation of the power generators at their maximum power point.

Generation is High & Power Demand is Low

Assume that the instantaneous generation is 1.5 kW which is the maximumpower point of the solar panels at this stage. However, the demand forpower is only 1 kW at this point. Hence if the system draws lesserpower, then the solar panels' voltage will increase, current will reduceand the panels will not operate at their maximum power point, leading tolikely wastage of potentially excess power generation. Since demand isless than supply, the microgrid has to decide where to channel theavailable excess supply.

In this case, the central controller (39) sends a signal to the fanout(38) indicating the amount of power consumption that the fanout (38)must increase. The fanout (38) then sends commands to individual PMDs,prioritized by increasing % of energy quotas used up to start chargingor increase the charging current of their local storage (7). Once thefanout (38) measures that the total power drawn has come to the levelcommanded by the central controller (39), the fanout (39) stops sendingthese commands. This process is repeated periodically to update the setof PMDs that must start or increase the rate of charging their localstorage. The prioritizing and equitable distribution technique accordingto the invention further allows operation of the solar panels at theirmaximum power point.

Although the foregoing description of the present invention has beenshown and described with reference to particular embodiments andapplications thereof, it has been presented for purposes of illustrationand description and is not intended to be exhaustive or to limit theinvention to the particular embodiments and applications disclosed. Itwill be apparent to those having ordinary skill in the art that a numberof changes, modifications, variations, or alterations to the inventionas described herein may be made, none of which depart from the spirit orscope of the present invention. The particular embodiments andapplications were chosen and described to provide the best illustrationof the principles of the invention and its practical application tothereby enable one of ordinary skill in the art to utilize the inventionin various embodiments and with various modifications as are suited tothe particular use contemplated.

1. A smart power grid system for a cluster of power management devices(PMD) used for efficient monitoring, controlling, metering includingequitable distribution of electrical power to the consumerscorresponding to demand-generation status by eliminating power theft,the smart power grid comprising one or more of non-conventional variableenergy generation sources, a traditional A.C. grid power, and/or acombination of conventional power grid including the non-conventionalpower generation source; a central controller, and a plurality of powermanagement devices (PMD), wherein each of the PMD comprises: a. amicrocontroller with a processor, a plurality of interfaces, a switchdriver, a tamper detector, and a logic for backup power source; b. acircuit protection means; c. a metering device to measure differenttypes of power for example AC, DC, or a combination of A.C. and D.C.(hybrid) supplied by the smart grid and consumed by the consumers; d. aplurality of switches for preventing overloading of the system, illegalconsumption of power, and monitor supply from the grid, each operable bythe switch driver; e. a local storage means having a charge monitoringcircuit for temporarily supplementing shortfall of generation or powerconsumption lower than generation; and f. a grid communication interfaceallowing the PMDs to communicate with the central controller beingphysically connected or remotely implement an intelligentdemand-response, identification of the area of power loss or theft,remote trouble shooting, and updating the payment for power consumption,the central controller in wireless or wired communications mode with themicrocontrollers are enabled to maximize the power output from thegenerators, prioritize each PMD through associated fanout, distributedstorage including equitable distribution of power, remote stackmanagement prevent power-theft.
 2. The smart power micro grid as claimedin claim 1, wherein the central controller is connected to a remotewireless transceiver.
 3. The smart power microgrid as claimed in claim1, comprising a central storage including a charge controller.
 4. Thesmart power microgrid as claimed in claim 1, wherein when the microgridis a AC grid interfaced to a power management device (B), the PMD (B) atuser end is provided with a battery charger (33), a DC-AC inverter (16),and at least one DC-DC converter.
 5. The smart power microgrid asclaimed in claim 1, wherein when the grid is a hybrid grid interfaced toa PMD(C), the PMD(C) is provided with one each submeter for meteringA.C. and D.C. supply respectively, including a combined converter. 6.The system as claimed in claim 1, wherein the central controller incommunication with PMD controller is enabled to: a. measure the totaloutput from the power generator; b. implement the process of maximumpower point (MPP) tracking; c. assign an energy capacity to each fanoutsand each PMDs based on the generation-consumption capacity; d. transmitsignals to the fanouts to increase power consumption if the PMD is notoperating at MPP, or to reduce power consumption when consumption ishigher than generation; e. prioritize each fanout based on theirpre-allocation capacities, power generation, and power consumption ateach point of time; f. prioritize each PMDs through the fanouts andtransmit signals to the PMDs to increase or decrease power consumptionbased on generation-consumption status including pre-assignedcapacities; g. allow the PMDs to consume excess power through chargingof local storage or supply to the consumers when generation is higher,alternatively allow the PMDs to stop charging their internal storageincluding rationing the supply to the consumers when generation is lowerthan demand; h. measure the power-drawn under the increased powerconsumption scenario, and further measure consumption or otherwise ofpower from the central storage by the PMDs; i. measure the status ofdecrease in power consumption by the PMDs when consumption is higherthan the generation; j. transmit further command to the PMDs to continueincrease their consumption under condition (viii), or stop supply ofpower to the PMDs when first decrease is not corresponding to lowergeneration and allow the PMDs to supply power to the consumers fromtheir local storage.
 7. The system as claimed in claim 1, wherein aplurality of power management units are provided in a stack to generatea variety of output voltages.
 8. The system as claimed in claim 1,wherein the system is activated and deactivated for a fixed period oftime by externally passing a waveform of a particular frequency orspecific commands readable by the system, and wherein after expirationof a fixed activated time, a power management device turns offautomatically.
 9. The system as claimed in claim 1, wherein the switchescomprise MOSFETs that turns the power management units on or off. 10.The system as claimed in any of the preceding claims, wherein thevariable energy generation source can be selected from a groupconsisting of solar panels, grid supply, micro wind generators, bicycledynamos and micro hydro power plants.
 11. A multipurpose powermanagement system, comprising: a singular or plurality of powermanagement devices which can be can be individually or plurallyactivated and deactivated, and each of the power management devicesbeing configured to be coupled to a variety of input energy sources; acontroller configured for providing regulated operational mechanisms, aplurality of convertors coupled to the battery of each power managementunit and configured for providing output voltages that are accessibleindividually; and a plurality of sensing circuits to sense externalsignals and provide selective activation or deactivation of the systemsaid plurality of PMDs are capable of communicating with each other andenable creation of a central grid power management system.
 12. Thesystem of claim 11, further comprising: a system housing; amicrocontroller, as a specific type of controller, which control signalsto provide for power management system's activation and/or deactivationof the devices through protection against theft detection and theoverloading or short circuiting of the devices compromising the system;a plurality of connectors positioned on a top and a bottom of thehousing to stack the plurality of power management units for higherpower output.
 13. The system of claim 11, further comprising: aplurality of filters coupled to the battery to filter signals foractivation/deactivation or recharging.
 14. The system of claim 11,wherein the charging controller with a comparator compares a batteryvoltage of an individual power management unit to a reference voltageand under condition of the battery voltage going above a referencevoltage. the comparator provides an output that determines whether thedevice should be on/off depending on whether there's a fault conditionor not.
 15. The system of claim 11, wherein the one or more input energysources charge the battery without required conversion or externalvoltage regulation.
 16. The system of claim 11, wherein power managementunits can be configured for a particular type of input energy source toenable secure rental through charging station businesses.
 17. The systemof claim 12, wherein in response to a power management unit beingconfigured for a particular type of input energy then the powermanagement units do not charge from another input energy source.
 18. Thesystem of claim 11, wherein a plurality of power management devices areprovided in a stack and generate a variety of output voltages.
 19. Thesystem of claim 11, further comprising: grid theft detection as one ofthe operational regulated mechanisms of the controller.
 20. The systemof claim 11, further comprising: overload detection capability as one ofthe operational regulated mechanisms of the controller.
 21. Amultipurpose power management system, comprising: a system housing; asingular or plurality of power management devices which can be can beindividually activated and deactivated, and each of the power managementdevices being configured to be coupled to a variety of input energysources as part of a distributed storage network for a central gridstructure; a controller or series of controllers configured forproviding the following capably regulated operational mechanisms a.charging the device's battery, b. grid theft detection, c. energyoverload detection; a plurality of convertors coupled to the battery ofeach power management unit and configured for providing output voltagesthat are accessible individually; a user interface component to enablevarious information feed backs on the units and overall system; aplurality of user switches for external activation and control; aplurality of filters coupled to the battery to filter signals foractivation/deactivation or recharging; an ability for one or more inputenergy sources coupled to the system wherein selected at least one offrom the following, solar panels, grid supply, micro wind generators,bicycle dynamos and micro hydro power plants; a plurality of filterscoupled to the battery to filter signals for activation/deactivation orrecharging; a reverse blocking diode coupled to the battery to preventcurrent from flowing from the battery to input energy sources; one ormore MOSFETs that turns the power management units on or off, and aplurality of sensing circuits to sense external signals and provideselective activation or deactivation of the system.
 22. A method foroperating a multipurpose power management system, comprising:implementation of a singular or plurality of power management deviceswhich can be can be individually or plurally activated and deactivated,and each of a power management device being operationally configured tobe coupled to a variety of input energy sources; a step for using acontroller or series of controllers configured for providing thefollowing regulated operational mechanisms a step for implementing aplurality of convertors coupled to the battery of each power managementunit and configured for providing output voltages that are accessibleindividually; a step towards enabling and using a user interfacecomponent to enable various information feed backs on the units andoverall system; a step for using a plurality of user switches forexternal activation and control; a step for use of a plurality offilters coupled to the battery to filter signals foractivation/deactivation or recharging; a step for implementing anability for one or more input energy sources coupled to the systemwherein selected at least one of from the following, solar panels, gridsupply, micro wind generators, bicycle dynamos and micro hydro powerplants; a step for using a plurality of filters coupled to the batteryto filter signals for activation/deactivation or recharging; a step forallowing use of a reverse blocking diode coupled to the battery toprevent current from flowing from the battery to input energy sources; astep for implementing one or more MOSFETs that turns the powermanagement units on or off, and a step for using a plurality of sensingcircuits to sense external signals and provide selective activation ordeactivation of the system.
 23. The method of claim 19 an operationalregulated mechanism step is comprising: of charging the power managementdevice's battery.
 24. The method of claim 19 an operational regulatedmechanism step is comprising: of monitoring the system's grid from theftthrough a power management device.
 25. The method of claim 19 anoperational regulated mechanism step is comprising: of detecting energyoverload on the individual devices and of the system as it relates tothe micro power grid.
 26. An automatized method of detecting power theftin a smart microgrid producing power and having a central controller andat least one power management device (PMD) having a microcontroller incommunication with the central controller and a light sensor, the methodcomprising the steps of: a. detection due to unauthorized access; b.transmission of a signal to the controller to shut down and detecttheft's point of emanation; c. temporarily turning off of the powersupply if the tamper condition is not eliminated.
 27. A process ofautomatically achieving the maximum power point tracking (MPPT) forvariable power generation source in a smart microgrid having at leastone central controller and a cluster of power management devices eachhaving a microcontroller, the process comprising the steps of: a.measuring the voltage and current of the power supply and measuring thepower output of the power generators by multiplying the voltage andcurrent; b. measuring upon receipt of signal from the fanouts on thestatus of percentage power change by the PMDs, by the centralcontroller; c. computing and transmitting a signal through a controllerto the fanouts for necessary modifications; d. providing a centralstorage on the system with a metering means.